The invention is directed to an apparatus for neutron detection wherein neutrons are detected by measuring current pulses produced by interaction of neutrons with boron nitride. The invention has particular application to the detection of thermal neutrons.
Current neutron electronic detector systems rely principally on tubes filled with gases such as 3He and BF3. These tubes are inefficient, bulky, fragile and complex to manufacture. Moreover, the low density of the gas phase is a major limitation on their use. Additionally, these prior art tubes have slow response times and are incapable of high resolution position sensing.
Generally, electronic detectors of nuclear radiation operate by exploiting the fact that incident radiation, by interaction in the detector volume, will create a charge pulse consisting of holes and electrons that can be separated under the influence of an electric field and the current detected by an external circuit. The conversion efficiency of solid state detectors is typically 100 to 1000 times greater than that of conventional gas-filled tubes consequently, solid state detectors are more sensitive than conventional gas-filled tubes. Moreover, solid state detectors are generally more compact, robust, and reliable than their gas-filled counterparts.
Newacheck et al. in U.S. Pat. No. 5,334,840 have shown that carbon infiltrated hexagonal boron nitride (hBN) can be used as a thermal neutron detector. The hexagonal boron nitride is used as a scintillator, to produce light in response to neutron conversion. The light is then detected in a secondary process, such as by exposing a photographic emulsion, or electronically with a photomultiplier or some other photon detection device. While this approach can be very efficient, timing and discrimination against gamma rays are poor. Moreover, detection relies on secondary means for detection rather than by a more efficient direct process.
Accordingly, the present invention provides for direct detection of neutrons by measuring the current produced when neutrons interact with hexagonal born nitride (hBN).